Microtriches of tetraphyllidean metacestodes from Western Mediterranean striped dolphins (Stenella coeruleoalba)

The tegumental structures of two types of tetraphyllidean plerocercoids and two types of merocercoids (Phyllobothrium delphini and Monorygma grimaldii) from Mediterranean striped dolphins, Stenella coeruleoalba, are described for the first time using scanning electron microscopy. The tegument of all of the specimens was fully covered with microtriches. Four basic types were found: filitriches, blade-like spinitriches of different sizes and shapes, cone-shaped spinitriches (with two parallel small projections of equal length at the apex), and crowned cylindrical spinitriches (with 6-7 small papillae forming a crown at the apex); the two latter types are newly described. The two types of plerocercoids had a similar morphology and distribution of microtriches; in addition, cilium-like projections appeared interspersed among the microtriches on the apical sucker, accessory suckers, and distal bothridial loculus. Merocercoids exhibited a greater variety of tegumental structures, especially on the distal bothridial loculus. Both merocercoid types had regularly spaced papillae or "buttons" on the accessory suckers and the distal bothridial loculus that were composed of a central cilium-like projection surrounded by numerous filitriches. However, crowned cylindrical spinitriches were specific to P. delphini and cone-shaped spinitriches were specific to M. grimaldii. Differences in the morphology and distribution of scolex microtriches of adult cestodes have been considered useful for species identification. A previous molecular study has suggested that P. delphini and M. grimaldii are actually different congeneric species. Our study has shown that significant differences in the morphology and distribution of microtriches occur between these species at the merocercoid stage.     

Phyllobothrium squali Yamaguti, 1952 (Tetraphyllidea,Phyllobothriidae): redescription and first record in the Black Sea

Phyllobothrium squali Yamaguti, 1952 is redescribed and illustrated on the basis of the holotype from Squalus acanthias from Japanese waters and specimens from the same host off the Bulgarian Black Sea coast (new geographical record). The species is characterised by: a scolex diameter of 2.9-4.3 mm, a glandular apical organ, foliose bothridia with folded and posteriorly bifid margins, accessory suckers of 286-367 micro m in diameter, 222-373 testes per proglottis, an oval cirrus-sac with a length of 354-655 micro m, the vagina opening anteriorly to the cirrus-sac, and the terminal part of vagina with a circular musculature. Specimens from Etmopterus spinax off Naples, Mediterranean Sea, recorded by Euzet (1959) as Crossobothrium squali, are redescribed and their identification not confirmed. P. squali is recognised as a specific parasite of S. acanthias; it is presently known only from Japanese waters, the Black Sea and the Irish Sea. Changes to the generic diagnosis of Phyllobothrium, as given by Ruhnke (1996a), are proposed in order to include the characters of P. squali.     

Two new tapeworms from the goblin shark Mitsukurina owstoni off Australia

Internal parasites are reported from the goblin shark Mitsukurina owstoni for the first time. The shark examined was a 190 kg male collected off of Ulladulla, New South Wales, Australia and deposited at the Australian Museum in Sydney. What appear to be 4 different species of tapeworms were recovered from the spiral intestine. These included two new species, Litobothrium amsichensis n. sp. (order Litobothridea) and Marsupiobothrium gobelinus n. sp. (order Tetraphyllidea), as well as one specimen of a trypanorhynch and one scolex of a second tetraphyllidean. The latter two species are unidentifiable without further material. The generic placement of the new tetraphyllidean is somewhat problematical; this genus was thought to be the most appropriate placement at present. The most conspicuous difference between the new litobothridean and the five other species in the order is that it possesses dorso-ventral projections on five rather than four or three anterior segments. The discovery of a litobothridean parasitising the goblin shark is consistent with the systematic placement of the Mitsukurinidae within the Lamniformes, and may preliminarily indicate close affinities between the Alopidae, Odontaspidae and Mitsukurinidae. The phyllobothriid differs from the five other species of Marsupiobothrium in its possession of extremely long bothridial peduncles, its lack of an arcuate cylindrical pad on the posterior bothridial margins and its possession of a marginal, distinct apical sucker rather than a submarginal, diffuse apical sucker on each bothridium. Four detached specimens of the new phyllobothriid retained tips of mucosal villi within their bothridia. From these specimens it appears that the peduncles allow this species to stretch its scolex for attachment to up to four villi simultaneously.     

A revision of Microbothriorhynchus Yamaguti, 1952 (Cestoda: Trypanorhyncha), with the redescription of M coelorhynchi Yamaguti, 1952 and the description of M reimeri n sp

The genus Microbothriorhynchus Yamaguti, 1952 is revised. Plerocerci of M. coelorhynchi Yamaguti, 1952 from the body-cavity of Brotula barbata (Bloch & Schneider) off the Angolan coast are re-described, and M. reimeri n. sp. from the body-cavity of Helicolenus maculatus (Cuvier) and Caelorinchus parallelus (Günther) from coastal waters off Mozambique is added to the genus. Both species are characterised in having an elongated, slightly craspedote scolex with small, collar-like bothridia, an elongate pars vaginalis and very long bulbs. The tentacular armature is heteroacanthous atypica, with eight principal hooks and intercalary hooks merging with a band of spiniform hooks on the external tentacle surface. The adult is unknown. Microbothriorhynchus is allocated to the Lacistorhynchidae Guiart, 1927, in having a blastocyst, two bothridia and a heteroacanthous atypica armature. Dasyrhynchus Pintner, 1928 and Pseudogrillotia Dollfus, 1969 are considered the most closely related genera, sharing characters such as the craspedote scolex, similar scolex proportions and hook patterns. Microbothriorhynchus appears to link the heteroacanthous atypica genera Grillotia Guiart, 1927 and Pseudogrillotia with the poeciloacanthous genus Dasyrhynchus.     

A new tetraphyllidean genus and species, Caulopaterapagei n. g., n. sp. (Tetraphyllidea: Phyllobothriidae), from the grey carpetshark Chiloscyllium punctatum Müller & Henle (Orectolobiformes: Hemiscylliidae)

A new genus and species of tetraphyllidean cestode, Caulopatera pagei n. g., n. sp., is described from the grey carpetshark Chiloscyllium punctatum Müller & Henle in Moreton Bay, Australia. The new genus is placed in the Phyllobothriidae, subfamily Phyllobothriinae. Caulopatera n. g. is distinct from all other phyllobothriine genera in having stalked, circular, non-loculate bothridia that lack an apical sucker, testes that are restricted to the region anterior to the cirrus-sac and circum-medullary vitelline follicles. The new genus most closely resembles Carpobothrium Shipley & Hornell, 1906, with which it shares non-loculate, stalked, unhooked bothridia without an accessory sucker and testes that are entirely anterior to the cirrus-sac, but differs from it in that it lacks a slit-like opening in each bothridium and flaps surrounding the opening. The possession of bothridial stalks is consistent with two cestode orders, the Tetraphyllidea and the Rhinebothriidea. The morphology of the bothridial stalks is consistent with other tetraphyllidean genera, in that Caulopatera possesses triangular bothridial stalks surrounding the back of the bothridia, indicating that it belongs in the Tetraphyllidea senso stricto, rather than in the recently recognised Rhinebothriidea.     

A new species of Acanthobothrium (Cestoda: Tetraphyllidea: Onchobothriidae) from the ocellate river stingray, Potamotrygon motoro (Chondrichthyes: Potamotrygonidae), in Argentina

Examination of the spiral intestines of 44 freshwater stingrays, Potamotrygon motoro, from tributary rivers of the Parana River in Argentina, allowed for the collection of specimens of an undescribed species of Acanthobothrium. Acanthobothrium ramiroi n. sp. can be distinguished from all other congeners by the combination of the following characters: asymmetrical hooks (medial and lateral hooks conspicuously different in size and form, with axial prong of medial hooks stouter than abaxial prong), hook size (total length of medial hooks up to 242 microm, total length of lateral hooks up to 239 microm), bothridia not fused to the scolex proper at posterior ends, worm size (51-84 mm long), and the presence of a conspicuous vaginal sphincter. The new species is different from all other species of Acanthobothrium in freshwater potamotrygonids, except Acanthobothrium terezae, in having conspicuous asymmetrical hooks. The main differences that allow for the distinction between A. ramiroi and A. terezae include hook size, the way the bothridia are attached to the scolex proper, and the shape of the older gravid segments. The discovery of a new species of Acanthobothrium from a potamotrygonid extends our understanding of the diversity of the genus in freshwater stingrays in South America.     

Two new species and a new phyllobothriid cestode genus from sharks of the genus Negaprion Whitley (Carcharhiniformes)

Alexandercestus n. g. (Cestoda: Tetraphyllidea) is erected for two cestode species found parasitising the two known species of lemon sharks (Carcharhiniformes: Negaprion spp.). This new genus differs from all other phyllobothriid genera except for Hemipristicola Cutmore, Theiss, Bennett & Cribb, 2011, Marsupiobothrium Yamaguti, 1952, Nandocestus Reyda, 2008, Orectolobicestus Ruhnke, Caira & Carpenter 2006, Orygmatobothrium Diesing, 1863, Paraorygmatobothrium Ruhnke, 1994 and Phyllobothrium van Beneden, 1849 in possessing uniloculate bothridia with an apical sucker and neck scutes. Alexandercestus differs from Orectolobicestus and Nandocestus in lacking marginal loculi on the bothridia, from Paraorygmatobothrium in possessing uninterrupted vitelline follicles at the level of the ovary and from Phyllobothrium in being euapolytic as opposed to anapolytic and in lacking posteriorly bifid bothridia. The new genus lacks the central accessory bothridial organ seen in specimens of Orygmatobothrium, and lacks the central bothridial accessory sucker of specimens of Marsupiobothrium. Alexandercestus spp. compare most favourably with specimens of Hemipristicola, especially with respect to aspects of proglottid morphology, but differ in possessing aristate gladiate spinitriches rather than serrate gladiate spinitriches on the proximal bothridial surface. In addition, the bothridia of Alexandercestus spp. are comparatively more fleshy and foliose than those in specimens of Hemipristicola. Two new species of Alexandercestus n. g. are described, Alexandercestus gibsoni n. sp. from Negaprion acutidens, collected from off northern Australia and the Marshall Islands, and Alexandercestus manteri n. sp. from N. brevirostris, collected off the islands of Bimini and the Florida Keys. The two new species differ in total length and vitelline follicle distribution. Bayesian inference and parsimony analysis of the D1–D3 region of the large nuclear ribosomal DNA of 17 published and seven novel sequences placed A. gibsoni as the sister taxon to a clade containing Hemipristicola gunterae Cutmore, Theiss, Bennett & Cribb, 2011 and species of Paraorygmatobothrium. This result supports the erection of Alexandercestus as a genus separate from Hemipristicola and Paraorygmatobothrium. At the present time, species of Alexandercestus are known only from hosts of the carcharhinid genus Negaprion Whitley; examination of extensive survey data suggests this may be the extent of the host distribution of this genus.     

Orygmatobothrium spp. (Cestoda: Tetraphyllidea) from triakid sharks in Argentina: redescription of Orygmatobothrium schmitti and description of a new species

Two species of Orygmatobothrium were found inhabiting triakid sharks collected from the coast of Buenos Aires Province, Argentina. Orygmatobothrium schmittii from Mustelus schmitti is redescribed, including new information on the microtrich pattern. Orygmatobothrium juani n. sp. from Mustelus fasciatus can be distinguished from all other species in the genus using the following combination of characters: worm length, number of proglottids, number of testes, testes distribution, size of eggs, ornamented egg shell, shape of bothridial cleft at level of the marginal accessory sucker, and the extension of vitelline follicles. Species in Orygmatobothrium share a common microtrich pattern with the distal bothridial surface covered with maisiform microtriches interspersed with filiform microtriches, a proximal bothridial surface covered with trifid microtriches, with a medial projection conspicuously larger than the lateral basal projections interspersed with filiform microtriches, an inner and outer surface of the accessory sucker and glandulomuscular organ covered with short filiform microtriches, the scolex proper and cephalic peduncle surface covered with bladelike microtriches, and the germinative zone and entire strobila covered with scutes formed by densely packed filiform microtriches. This general configuration is basically similar to the microtrich pattern described in species of Orectolobicestus and Paraorygmatobothrium.     

A new species of Ditrachybothridium (Cestoda: Diphyllidea) from Galeus sp. (Selachii, Scyliorhynidae) from the south Pacific Ocean, with a revision of the diagnosis of the order, family, and genus and notes on descriptive terminology of microtriches

Ditrachybothridium piliformis is a new species from the spiral intestine of a cat shark, Galeus sp., from the southern Pacific Ocean. This is only the second species assigned to Ditrachybothridium. It differs from the type species D. macrocephalum in lacking spines on the scolex, a character originally used to diagnose the genus. The diagnoses of the Ditrachybothridiidae and of Ditrachybothridium have been revised to reflect this difference. This new species is further differentiated from the type species in its possession of pectinate spinitriches on the tegument of the scolex. The holdfast structures of this species are weakly muscularized, with no membrane-bound layer of radial muscles, indicating that the holdfast structures are bothria rather than bothridia as described in the most recent literature. Several reports for other species have indicated the same situation in other diphyllideans. The diagnosis of the order has been revised to reflect this finding.     

Proemotobothrium n. g. (Cestoda: Trypanorhyncha), with the redescription of P. linstowi (Southwell, 1912) n. comb. and description of P. southwelli n. sp.

A new genus, Proemotobothrium (Trypanorhyncha: Otobothriidae), is erected to contain P. linstowi (Southwell, 1912) n. comb. (syn. Otobothrium magnum Southwell, 1924) and P. southwelli n. sp. The new genus is characterised by two bothridia, paired bothridial pits, an acraspedote scolex, elongate bulbs, four hooks per principal row, hooks 4 (4') being small and uncinate, a single, filiform, intercalary hook between each principal row and by the arrangement, in tandem, of the two or three extra hooks of the armature of the external surface of the tentacle, a pattern previously known only in the family Mixodigmatidae. The two species are distinguished from one another on the basis of measurements of the scolex and bulbs, the sizes of the hooks of the principal rows and by the number and size of the additional hooks in the linear arrays on the external surface of the tentacle.     

Anthobothrium lesteri n. sp. (Cestoda: Tetraphyllidea) in Carcharhinus melanopterus from Heron Island, Australia, with comments on its site, mode of attachment, reproductive strategy and membership of the genus

Anthobothrium lesteri n. sp. in Carcharhinus melanopterus from Heron Island, Australia is described and figured. A combination of characters, namely the number of testes, a weakly laciniate strobila and mature proglottis which is conspicuously longer than wide distinguishes it from other species that appear to be consistent with van Beneden's original concept of Anthobothrium . The scolex and the peduncle are relatively small and frail when compared with the rest of the strobila and with the detached proglottis. A myzorhynchus is absent and the stalked, undivided, simple bothridia have thickened margins. Two circular areas of muscles, which resemble accessory suckers, occur in the centre of each bothridium. There is a distinct cephalic peduncle with spiniform blade-like microtriches followed by craspedote proglottides which have a posterior four-lobed velum. Apolysis is well developed and the oncosphere has a polar filament and a dense covering of spines. Comments are made on the site, the mode of attachment, an aspect of the reproductive strategy of the new species in relation to intestinal eversion in some sharks, and membership of the genus.     

GEOGRAPHICAL VARIATION OF THE PARASITE, PHYLLOBOTHRIUM DELPHINI (CESTODA), IN BALL'S PORPOISE, PHOCOENOIDES DALLI, IN THE NORTHERN NORTH PACIFIC, BERING SEA, AND SEA OF OKHOTSK

Prevalence of the larval cestode, Phyllobothrium delphini , was estimated from 2,445 Dall's porpoise, Phocoenoides dalli , from the incidental take of the Japanese high seas salmon drift-net fishery in the northwestern North Pacific Ocean, Bering Sea, and a local hand harpoon fishery in the southern Sea of Okhotsk. Prevalence of P. delphini was 22.7% in the northwestern North Pacific Ocean and 1.4% in the Bering Sea. This parasite was not found in the southern Sea of Okhotsk. Geographical differences in the prevalence of P. delphini may be due, at least in part, to regional differences in abundance of elasmobranchs known to feed on marine mammals and suspected as hosts of the parasite. Estimated intensity of infection of individual porpoises by P. delphini was low (estimated mean intensity of 3.5 plerocercoids per animal). This is a low intensity of infection compared to other species of small cetaceans studied and may be due to both differences in regional abundance of elasmobranchs and the comparatively short life span of P. dalli.     

Two new species of Echinobothrium (Cestoidea: Diphyllidea) from myliobatiform elasmobranchs in the Gulf of California, México

Two new species of diphyllidean cestodes, Echinobothrium mexicanum n. sp., and Echinobothrium fautleyae n. sp., are described, the former from the spiral intestines of the bat rays Myliobatis californicus and Myliobatis longirostris and the latter from the spiral intestine of the cownose ray Rhinoptera steindachneri, all caught in the Gulf of California, México. Echinobothrium mexicanum is most easily distinguished from the majority of the species of the genus by the number of large apical hooks in each dorsoventral group (23) and from the remainder in the number of lateral hooklets in each group on the scolex. Echinobothrium fautleyae differs conspicuously from all other members of the genus in that the first and last lateral hooklets in each group are distinctly larger than the other hooklets in each group. Serial sections of the scoleces of these 2 new species confirm that the attachment structures on the scolex are bothria, rather than bothridia, as has been described in other species in the genus, suggesting that the attachment structures of the scolex should be examined in more detail in the genus in general. Palmate microtriches of various forms cover the proximal bothrial surfaces of both new species and are also found on the dorsal bothrial surfaces of E. fautleyae. The distal bothrial surfaces of E. mexicanum are covered with slender spiniform and short filiform microtriches. The cephalic peduncles of both species possess short filiform microtriches only. Comparison of these 2 new species with the other 3 species in this genus that have been examined with SEM suggests that the various forms and distributions of these microtriches is unique in each of these 2 species. We believe these features will prove to be taxonomically useful.     

The Florida amphioxus (Cephalochordata) hosts larvae of the tapeworm Acanthobothrium brevissime: natural history,anatomy and taxonomic identification of the parasite

Plerocercoid larvae of a tapeworm are frequently found in the hindgut lumen of the Florida amphioxus (Branchiostoma floridae) in central west Florida. About three‐quarters of the adult amphioxus are parasitized. On average, each adult amphioxus hosts about five tapeworm larvae. The residence time of the parasites in the amphioxus gut appears to be in the order of several months, which is considerably shorter than the potential lifetime of the host. The living larvae range in length (when fully extended) from 300 to 850 µm and are approximately cone‐shaped, tapering to a point posteriorly and bearing a single large sucker anteriorly. Toward the anterior end of the body are four hookless bothridia, each indented by three loculi plus an inconspicuous accessory sucker. The larvae initiate the early stages of hook formation when they are cultured for a few days in urea‐saline (mimicking the gut fluid of the definitive host, which is an elasmobranch). The tapeworm larvae are identifiable to genus and species on the basis of correspondences between their nuclear ribosomal DNA genes and those of adult specimens of Acanthobothrium brevissime recovered from the spiral valve of a stingray from the same environment.     

Comparison of microthrix ultrastructure and morphology on the plerocercoid and adult scolex of Calliobothrium cf. verticillatum (Tetraphyllidea: Onchobothriidae)

The distal bothridial surfaces of adult triloculate onchobothriids are covered with short structures that have been tentatively classified as very short filitriches, but this hypothesis has never been tested. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate microthrix morphology in the plerocercoid and adult forms of Calliobothrium cf. verticillatum, a triloculate onchobothriid tapeworm from Long Island Sound (Connecticut). Plerocercoids of C. cf. verticillatum were collected from the anterior midgut ceaca of Pagurus pollicaris Say, 1817 (flat-clawed hermit crab), and adults were collected from the spiral intestine of the dusky smooth hound Mustelis canis (Mitchell, 1815). Two plerocercoids and 2 adults were examined using SEM; 2 plerocercoids and 2 adults were examined using TEM. Microthrix distribution and morphology (including measurements of total length, base length, shaft length, and base width) were investigated on all surfaces of the plerocercoid and adult scolex. Slender filitriches and large bladelike spinitriches were observed extending from the tegument of plerocercoid and adult forms. The filitriches were found to have significantly narrower bases than the spinitriches (65-167 nm vs. 466-1,936 nm, respectively). The scolex proper of the plerocercoid and adult forms were found to have filitriches of medium-length and bladelike spinitriches. The distal bothridial surfaces differed dramatically in microthrix morphology between plerocercoid and adult forms; on the distal surfaces of the plerocercoids were long filitriches and bladelike spinitriches. However, the distal surfaces of the adults had short structures (previously hypothesized to be short filitriches) and a few bladelike spinitriches. Serial transverse sections revealed that the short structures on the distal bothridial surfaces of the adults were homologous with filitriches. They included all of the structural components of a filithrix as well as a base width that conformed to the filitriches found on other surfaces. The bothridial margins of the plerocercoid and adult forms had a microthrix pattern similar to that seen on the proximal bothridial surfaces except that the filitriches on the margins were significantly longer than those found anywhere else on the bothridia. The most dramatic difference between the plerocercoid and adult forms occurred on the distal bothridial surfaces, where the filitriches of the adult cestodes were significantly shorter and narrower, and the spinitriches were almost entirely lacking.     

A New Genus of the Tetraphyllidean Cestodes from <Emphasis Type="Italic">Dasyatis sephen</Emphasis> Forsskal, 1775 Captured from Digha Coastal Water,Bay of Bengal,India

Aloculibothrium dasyatii n. gen. n. sp. is described from the spiral intestine of Dasyatis sephen Forsskal, 1775 captured at Digha coastal waters, Bay of Bengal, India. This species is placed under the famil Onchobothriidae (Braun, 1900) and erected a new genus Aloculibothrium to accommodate this specimen. The body is 24.22–36.58 mm long and with 310–325 proglottids; scolex rectangular with two parts; anterior bearing four bothridia with paired bifurcated hooks, divided into inner and outer prong and posterior with fleshy collar. The cestode has been compared with all the existing twelve different valid genera under the family Onchobothriidae but to accommodate the present specimens a new genera Aloculibothrium is erected.     

Scyphophyllidium uruguayense n. sp. (Eucestoda: Tetraphyllidea) in Mustelus mento (Cope, 1877) (Chondrichthyes: Carcharhiniformes: Triakidae) from La Paloma, Uruguay.

A new species of Scyphophyllidium inhabits Mustelus mento near La Paloma, Uruguay. It resembles Scyphophyllidium giganteum from the Atlantic Ocean and specimens identified as S. giganteum from California by having anapolytic strobilae 155-258 mm long, 250-300 craspedote proglottids, scoleces 1.2-1.4 mm wide, necks 34-41 mm long, immature and mature proglottids wider than long, gravid proglottids wider than long to longer than wide, genital pores averaging 28% of proglottid length from the anterior end, relatively flat ovaries with digitiform lobes reaching the lateralmost extent of the testicular field, vitellaria in 2 fields converging toward the proglottid midline, straight and short cirrus sacs, and postvaginal vas deferens. The bothridia of the new species have accessory bothridial suckers that are smaller than those of California specimens; European specimens reportedly lack accessory bothridial suckers. The new species possesses a uterine duct that joins the uterus at the level of the genital atrium and ventral osmoregulatory ducts medial rather than lateral to the dorsal ducts, an arrangement described for Californian but not European specimens. It differs from both European and Californian specimens by having longer cirri, more testes per proglottid, prominent scales covering the neck, and vaginae and uterine ducts coiled immediately preovarially. Pithophorus, Marsupiobothrium, and Scyphophyllidium may form a clade.